body-1px($color)
  position:relative
    &:after
     display:block
     position: absolute
     left:0
     bottom:0
     width:100%
     border-top:1px solid $color
     content:''
border-none()
  &:after
    display none
bg-image($url)
  background-image: url($url+"@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3),(-webkit-min-device-pixel-ratio: 3)
    background-image: url($url+"@3x.png")
